Like multiple sclerosis in humans, EAE susceptibility is genetically determined, both MHC- and non-MHC-linked genes are implicated in susceptibility. The goal of this proposal is to study the cellular immune response to myelin proteins in genetically resistant and susceptible strains of mice and to gain insight into the critical steps involved in regulation of EAE pathogenesis. While T lymphocytes from EAE-susceptible strains of mice have been studied in great detail, until this application no one has cloned myelin-specific T cells from EAE-resistant strains. Furthermore, our data demonstrate that some of the myelin-specific T cell clones derived from EAE-resistant animals are capable of inducing clinical and histological sighs of EAE. Building on these observations we propose to further explore the mechanisms of genetic resistance to EAE, define the conditions by which T cells induce disease and evaluate the role of cytokine production in encephalitogenicity. Initial results on a panel of 11 clones indicated that expression of RNA transcripts for a proinflammatory cytokine, TCA3, or its alternate splice form (P500) correlated with EAE induction. We defined experimental conditions under which an individual clone could be either encephalitogenic or non-encephalitogenic, under these conditions there was a dramatic increase in TCA3 expression. To further define the role of this cytokine in auto immune disease we will use antibodies to modulate disease and genetic manipulation of myelin-specific T cell clones to inhibit the cytokine genes which are involved in EAE pathogenesis. The final aim evaluates the ability of glial cells (astrocytes and microglia) to serve as antigen presenting cells to our panel of T cell clones. Glial cells can function as APC for proliferative T cell responses and release of cytokines including TNF and IL3/CM-CSF. However, neither microglia nor astrocytes induce IL2 synthesis. The failure to induce IL-2 is associated with the induction of T cell anergy. We will examine anergy induction by glial APC from EAE susceptible and resistant strains and define the molecules responsible for this phenomenon.